Formulation of bacteriological growth medium from locally available materials to enhance practical-based learning in tertiary institutes

Abstract

Microbiology is one of the key disciplines in tertiary institutions. It involves the study of bacteria on both a theoretical and practical basis; however, practical lessons in most institutions are not carried out due to the unavailability of materials used to culture microorganisms. This is attributed to the high cost of the bacteriological culture media. Thus, this study aimed to formulate affordable microbial growth media from locally available materials to enhance and sustain microbiology practical-based teaching in Uganda. The microbial growth media were formulated from Irish potatoes, soya beans, cassava flour, and coconut juice. Three formulations (A, B, C) of the solid media were made using three different material combination ratios. Fresh coconut juice was used to formulate broth media and to culture MacFarland equivalents of bacteria on microtiter plates. The Tryptic Soy Agar (TSA), and Broth (TSB) were used as the control. The media formulations were evaluated for supporting microbial growth using Escherichia coli and Staphylococcus aureus and this was achieved by carrying out bacterial counts on each medium. Furthermore, the in-house formulated solid growth media were evaluated for supporting antimicrobial susceptibility assays, and the Mueller Hinton Agar (MHA) was used as the control. Meropenem, chloramphenicol, amoxicillin, Nalidixic acid, Gentamicin, and Erythromycin were used as the standard antibiotics while the lemon juice and garlic juice extracts were used as the locally available materials with antibacterial activity. The disc diffusion and agar well diffusion methods were used for the standard antibiotics and plant extracts. The mean bacterial percentage recoveries were 8.4479, 8.1300, and 8.2657% for formulations A, B, and C respectively; comparable to 9.5680 % obtained from TSA. Antimicrobial susceptibility tests revealed the in-house formulated solid media allowed the diffusion of antibiotics and plant extracts. Therefore, the locally formulated media can be used in the practical and project-based teaching of microbiology/prokaryotes in tertiary institutions and upper secondary thereby enhancing the implementation of the competence-based curriculum.